如何將linq查詢轉換爲非查詢表達式？

Question

我用EF6，我有這樣的LINQ到實體查詢：

from s in SensorObservationEntities.SensorsMeasures 
      group s by s.SensorUnitId into g 
      let latest = g.OrderByDescending(s => s.MeasureDate).FirstOrDefault() 
      select latest 

我怎麼能它convet非查詢表達式？

Answer 1

如果要將此轉換爲方法的語法版本，你能做到這一步一步來。我想先在結束並通過工作開始：

1. select到Select定義源：

   .Select(g => g.OrderByDescending(s => s.MeasureDate).FirstOrDefault()); 
   

2. group爲GroupBy：

   .GroupBy(s => s.SensorUnitId) 
   .Select(g => g.OrderByDescending(s => s.MeasureDate).FirstOrDefault()); 
   

3. from的來源

   SensorObservationEntities.SensorsMeasures 
   .GroupBy(s => s.SensorUnitId) 
   .Select(g => g.OrderByDescending(s => s.MeasureDate).FirstOrDefault()); 
   

Answer 2

你的意思是方法的語法：

SensorObservationEntities.SensorsMeasures.GroupBy(g => g.SensorUnitId) 
      .Select(y => y.OrderByDescending(x => x.MeasureDate).FirstOrDefault());